3 files changed, 43 insertions, 6 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 0ac47f2834d1..3f75895c919b 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -106,6 +106,7 @@ struct __prelim_ref {
         struct btrfs_key key_for_search;
         int level;
         int count;
+        struct extent_inode_elem *inode_list;
         u64 parent;
         u64 wanted_disk_byte;
 };
@@ -166,6 +167,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
         else
                 memset(&ref->key_for_search, 0, sizeof(ref->key_for_search));
 
+        ref->inode_list = NULL;
         ref->level = level;
         ref->count = count;
         ref->parent = parent;
@@ -181,14 +183,21 @@ static int add_all_parents(struct btrfs_root *root, struct btrfs_path *path,
                                 const u64 *extent_item_pos)
 {
         int ret;
-        int slot;
+        int slot = path->slots[level];
         struct extent_buffer *eb = path->nodes[level];
         struct btrfs_file_extent_item *fi;
+        struct extent_inode_elem *eie = NULL;
         u64 disk_byte;
         u64 wanted_objectid = key->objectid;
 
 add_parent:
-        ret = ulist_add(parents, eb->start, 0, GFP_NOFS);
+        if (level == 0 && extent_item_pos) {
+                fi = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
+                ret = check_extent_in_eb(key, eb, fi, *extent_item_pos, &eie);
+                if (ret < 0)
+                        return ret;
+        }
+        ret = ulist_add(parents, eb->start, (unsigned long)eie, GFP_NOFS);
         if (ret < 0)
                 return ret;
 
@@ -202,6 +211,7 @@ add_parent:
          * repeat this until we don't find any additional EXTENT_DATA items.
          */
         while (1) {
+                eie = NULL;
                 ret = btrfs_next_leaf(root, path);
                 if (ret < 0)
                         return ret;
@@ -346,6 +356,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                 ULIST_ITER_INIT(&uiter);
                 node = ulist_next(parents, &uiter);
                 ref->parent = node ? node->val : 0;
+                ref->inode_list =
+                        node ? (struct extent_inode_elem *)node->aux : 0;
 
                 /* additional parents require new refs being added here */
                 while ((node = ulist_next(parents, &uiter))) {
@@ -356,6 +368,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
                         }
                         memcpy(new_ref, ref, sizeof(*ref));
                         new_ref->parent = node->val;
+                        new_ref->inode_list =
+                                        (struct extent_inode_elem *)node->aux;
                         list_add(&new_ref->list, &ref->list);
                 }
                 ulist_reinit(parents);
@@ -879,7 +893,7 @@ again:
                 }
                 if (ref->count && ref->parent) {
                         struct extent_inode_elem *eie = NULL;
-                        if (extent_item_pos) {
+                        if (extent_item_pos && !ref->inode_list) {
                                 u32 bsz;
                                 struct extent_buffer *eb;
                                 bsz = btrfs_level_size(fs_info->extent_root,
@@ -889,10 +903,22 @@ again:
                                 BUG_ON(!eb);
                                 ret = find_extent_in_eb(eb, bytenr,
                                                         *extent_item_pos, &eie);
+                                ref->inode_list = eie;
                                 free_extent_buffer(eb);
                         }
-                        ret = ulist_add(refs, ref->parent,
-                                        (unsigned long)eie, GFP_NOFS);
+                        ret = ulist_add_merge(refs, ref->parent,
+                                              (unsigned long)ref->inode_list,
+                                              (unsigned long *)&eie, GFP_NOFS);
+                        if (!ret && extent_item_pos) {
+                                /*
+                                 * we've recorded that parent, so we must extend
+                                 * its inode list here
+                                 */
+                                BUG_ON(!eie);
+                                while (eie->next)
+                                        eie = eie->next;
+                                eie->next = ref->inode_list;
+                        }
                         BUG_ON(ret < 0);
                 }
                 kfree(ref);
diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c
index 17e68bdc307c..2ef59400ad6e 100644
--- a/fs/btrfs/ulist.c
+++ b/fs/btrfs/ulist.c
@@ -146,11 +146,20 @@ EXPORT_SYMBOL(ulist_free);
 int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
               unsigned long gfp_mask)
 {
+        return ulist_add_merge(ulist, val, aux, NULL, gfp_mask);
+}
+
+int ulist_add_merge(struct ulist *ulist, u64 val, unsigned long aux,
+                    unsigned long *old_aux, unsigned long gfp_mask)
+{
         int i;
 
         for (i = 0; i < ulist->nnodes; ++i) {
-                if (ulist->nodes[i].val == val)
+                if (ulist->nodes[i].val == val) {
+                        if (old_aux)
+                                *old_aux = ulist->nodes[i].aux;
                         return 0;
+                }
         }
 
         if (ulist->nnodes >= ulist->nodes_alloced) {
diff --git a/fs/btrfs/ulist.h b/fs/btrfs/ulist.h
index 62d2574f775a..f1b1bf00c5a9 100644
--- a/fs/btrfs/ulist.h
+++ b/fs/btrfs/ulist.h
@@ -67,6 +67,8 @@ struct ulist *ulist_alloc(unsigned long gfp_mask);
 void ulist_free(struct ulist *ulist);
 int ulist_add(struct ulist *ulist, u64 val, unsigned long aux,
               unsigned long gfp_mask);
+int ulist_add_merge(struct ulist *ulist, u64 val, unsigned long aux,
+                    unsigned long *old_aux, unsigned long gfp_mask);
 struct ulist_node *ulist_next(struct ulist *ulist,
                               struct ulist_iterator *uiter);